Though I think it perfectly fair to make educated guesses about what may be in store for us, based on past experience (in this case, PJ's treatment of Gandalf's 'magic' in LOTR), hints from merchandise, etc.

There was a significant amount of such speculation prior to LOTR, and a non-trivial amount of that speculation turned out to be true. So, it's not wholly futile.

Plus, isn't this at least part of what boards like these are for? To speculate, based on small scraps of information, as opposed to testing hypotheses, based on large amounts of evidence?

Ainur may very well be correct in his fears. Or he may not be.

But let's not judge his mad speculation too harshly. It is a way of passing the time, and preparing (or desensitizing) oneself for what's to come.